1. Technical Field
The present disclosure relates to a power transmission apparatus and a wireless power transmission system that send AC power in a non-contact manner by utilizing electromagnetic induction between a power transmission coil and a power reception coil.
2. Description of the Related Art
These days, various mobile devices, for example, cell phones, are becoming widespread, and power consumption in mobile devices is increasing due to their enhanced functions and performance and an increase in the variety of the content. If power consumption in a mobile device operating with a limited capacity of batteries increases, the operating time of the mobile device decreases. As a technology for compensating for a limited capacity of batteries, a wireless power transmission system is attracting a lot of attention. A wireless power transmission system sends AC power in a non-contact manner from a power transmission apparatus to a power reception apparatus by utilizing electromagnetic induction between a power transmission coil of the power transmission apparatus and a power reception coil of the power reception apparatus. Particularly in a wireless power transmission system using a resonance-type power transmission coil and power reception coil, high transmission efficiency can be maintained even when the power transmission coil and the power reception coil are displaced from each other. Accordingly, the application of such a wireless power transmission system in various fields is being expected.
In a wireless power transmission system, when charging batteries, the optimal voltage and current to be applied to the batteries changes over time in accordance with the amount of charged energy. While the batteries are being charged, the temperature of the batteries may rise, in which case, it is necessary to reduce the amount by which the batteries are charged. In this manner, in the case of battery charging, for performing optimal power transmission, it is necessary to provide feedback of temperature information and charge amount information, as well as information concerning a desired voltage and current, from a power reception apparatus to a power transmission apparatus.
Examples of the above-described related art are disclosed in Japanese Unexamined Patent Application Publication No. 2010-16985 and International Publication Nos. 2012/081519 and 2012/164744 pamphlets.